Thin electronic label and method for making same

ABSTRACT

The aim of this invention is to provide a thin flexible card or electronic label, wherein are mounted electronic components to provide good electric connection between component contacts and card conductors. The aim of this invention is also to provide a manufacturing method for this type of card or electronic label.  
     The card or electronic label, according to the invention, is produced by assembling at least one thin, flexible substrate ( 7 ), a conductive layer ( 4 ) and an adhesive layer ( 1 ), and comprising at least one electronic component ( 11 ). Said card is characterized in that the substrate ( 7 ) includes at least one window ( 8 ) wherein is housed the electronic component ( 11 ), the adhesive layer ( 1 ) maintains the conductive layer ( 8 ) on the substrate, the conductive layer ( 4 ) extends partially into the window&#39;s surface ( 8 ) so as to form at least one electric contact ( 4 ′) whereon the electronic component ( 11 ) is connected. The substrate ( 7 ) has a thickness preferably selected on the basis of the greatest height of the component to be mounted.

[0001] This invention concerns a thin card or electronic labelcomprising at least one electronic component and also a method formanufacturing this type of card.

[0002] The invention concerns a card with or without external contact oran electronic label. Electronic label is understood to mean an assemblycomprising at least a support, an antenna and an electronic component,generally a chip. The card or the electronic label according to theinvention is present in many applications as means for identification,control or payment.

[0003] The object of this invention is focused particularly on cards oron thin, flexible cards in which at least one electronic component ismounted. An electronic component is an element such as: a chip, acapacitor, a resistor, a fuse, a battery, a display, a fingerprintcontroller (“fingertip”) or any other similar element.

[0004] Those skilled in the art know of cards or electronic labels onwhich components are mounted in an insulating support called asubstrate, on which tracks and connector areas are engraved inconductive material (generally made of copper). The components aregenerally adhered, and then their contacts are soldered onto the tracksor on the conductive connector areas of the substrate. In order toprotect the components and the circuit wired in this way, an epoxy resinis cast on all or part of the surface so as to coat the whole circuit.

[0005] The document EP1167068 describes a connection by means ofpressing the chip contacts into the tracks engraved on a substrate andoriginating from a coil-shaped antenna. The chip connection is carriedout without soldering thanks to spikes previously added on the contactsand intended to be pushed into the metal of the conductive track. Theassembly is then coated with resin and/or covered with an insulatinglayer.

[0006] Both types of known cards or electronic labels described abovepresent the drawbacks of having on one hand a high thickness which isdifficult to control during manufacturing and on the other hand alimited flexibility. In fact, components have different heights and thecoating thickness must correspond to the maximum height reached by atleast one of the components in order to assure an acceptable flatness ofthe card. As information, the usual thickness of a card is 0.76 mm inaccordance with the ISO 7816 standards.

[0007] In the second case where the contacts of the component are fixedby pressing into the conductors engraved in the substrate, the qualityof contact-conductor connection varies depending on the mechanicalconstraints to which the card is subjected such as flexion ordistortion.

[0008] The aim of this invention is to avoid the drawbacks describedabove, namely to obtain a flat, thin and flexible card or electroniclabel that provides a minimal waste ratio during manufacturing. Thisparticularly concerns the quality of the electric connection between theelectronic component (s) and the tracks on the conductive part of thecard.

[0009] It is also another aim of this invention to propose amanufacturing method for this type of card or electronic label.

[0010] This aim is reached with a card or electronic label obtained byassembling at least one thin flexible substrate, a conductive layer andan adhesive layer, and comprising at least one electronic component,said conductive layer being formed by conductive tracks defining anantenna, characterized in that the substrate includes at least onewindow in which the electronic component is housed, the adhesive layermaintains the conductive layer on the substrate and the conductive layerextends partially in the surface of the window in order to form at leastone electrical contact whereon the electronic component is connected.

[0011] The card or the electronic label according to the invention ismade up of an insulating layer called substrate, the thickness of whichis preferably selected according on the basis of the greatest height ofthe component to be mounted. This selected substrate's thicknessdetermines the final aspect of the card or label, namely if thecomponent will show on the card surface, form a relief or a cavity onthe card.

[0012] Said substrate includes windows that are used for housing theelectronic components. The dimensions of the windows are determinedaccording to the dimensions of the component and according to thenecessary space around the latter. According to a first embodiment, thespace around the component is minimal in order to maintain theelectronic component temporarily in its housing before the solderingphase.

[0013] According to another embodiment, the space is larger in order tofill it with binder or so that it can receive more than one component.

[0014] The component contacts are connected to conductive tracksengraved on at least one face of the substrate. These contacts areconnected either by means of a direct connection on the conductivetracks, namely on the prolongation of the conductive layer in thewindow, or through a conductive bridge. Various configurations arepossible:

[0015] both component contacts are connected to the conductive layer bydirect connection on the conductive tracks,

[0016] a contact is connected to the conductive layer by directconnection while the other component contact is connected on a moredistant connection area of the conductive layer by means of an insulatedconductive bridge that passes over other tracks,

[0017] the conductive bridge, connected to a component contact, passesbeside the component inside the substrate's window where said componentis housed in order for be situated on the opposite side of substrate.The bridge is connected on the conductive face by crossing the substrateaccording to a method known by those skilled in the art. The othercomponent contact is connected to the conductive layer by directconnection or by means of another bridge as mentioned previously.

[0018] A card or an electronic label formed in this way has a thicknessthat corresponds to the maximum height measured in the set of componentsused, to which it is necessary to add the thickness of the conductivelayer. Its flexibility is all the more great because its thickness isreduced. The mounted components penetrate the thickness of the substrateand are thus protected from mechanical attacks.

[0019] The present invention also has as object a method formanufacturing cards or electronic labels carried out by assembling atleast one thin, flexible substrate, a conductive layer and an adhesivelayer, and comprising at least one electronic component, said conductivelayer being made up of conductive tracks defining an antenna,characterized in that it includes the following steps:

[0020] formation of at least one segment in the conductive layer,

[0021] formation of at least one window in the adhesive layer,

[0022] formation of at least one window in the substrate, said windowbeing intended to receive the electronic component,

[0023] superimposition and lamination of the adhesive and conductivelayers on the substrate in order to make correspond the openings madepreviously,

[0024] execution of an electric circuit made up of a plurality oftracks, and formation of at least one connection surface for theelectronic component located in the window of the substrate,

[0025] positioning and connection of the electronic component in thewindow formed for that purpose in the substrate.

[0026] The aforementioned segment in the conductive layer is an openinggenerally made by stamping or by etching in the conductive layer. Thisopening has a shape and dimensions that depend on the configuration ofthe contacts of the electronic component. It serves to create aconnection surface for these contacts during the execution of theelectric circuit.

[0027] The result of the aforementioned characteristics is a card or anelectronic label manufacturing method that includes at least oneelectronic component, in accordance with the invention, and thatrequires a reduced number of operations that furthermore areinexpensive. The steps of the manufacturing method can be groupedtogether and/or carried out in a different order or some can even beeliminated according to the applied characteristics describedhereinafter. The properties required for this type of card or electroniclabel are guaranteed with this method: high flexibility, highreliability due to the efficient holding of the contacts of theelectronic components.

[0028] The size of the window in the adhesive layer is determined insuch a way that it is possible to remove the glue present in the areawhere the electronic component will be mounted without removing the gluepresent under the conductive tracks. This definition permits a widechoice of shapes for the adhesive layer formation means.

[0029] According to another variant for the manufacturing method of acard or an electronic label in accordance with the invention, it isforeseen not to cut windows in the adhesive layer as described in thefirst step of said process. In fact, the residual glue present on thesurfaces reserved for component contacts, said surfaces that are presentin the windows cut in the substrate, can be eliminated using:

[0030] chemical means before positioning of electronic components

[0031] evaporation or exhausting during the electronic componentconnection (soldering, hot bonding or thermo-compression).

[0032] According to another variant of the manufacturing method of acard or an electronic label in accordance with the invention, it isforeseen to substitute the adhesive film used to form the adhesive layerwith a liquid adhesive deposited on the conductive layer bysilk-screening with protective materials for the windows that preventthe depositing of adhesive on the surfaces reserved for componentcontacts.

[0033] According to another variant of a manufacturing method of a cardor an electronic label in accordance with the invention, it is foreseento deposit the adhesive layer on the substrate by silk-screening withprotected areas for the windows. The adhesive layer can also bedeposited on the entire substrate surface (without protectivematerials), before the cutting of the windows. The windows formationstep in the substrate also allows the removal of the glue in this area.The conductive layer is then assembled on the substrate, leaving theconductive layer contact surfaces reserved for the connection componentsfree from glue.

[0034] One of the characteristics of the invention is that theconnection part of the electronic component will not appear inover-thickness of the conductive layer and the substrate, which isgenerally the case according to the examples in the prior art.

[0035] The invention will be better understood thanks to the followingdetailed description and with reference to the annexed drawings that aregiven as a non-limitative example, in which:

[0036]FIG. 1 represents an adhesive film with cuttings of windows,

[0037]FIG. 2 represents an assembly made up of the adhesive filmsuperimposed on a film of conductive material,

[0038]FIG. 3 represents the assembly made up of an adhesive film and theconductive film with the cuttings of segments,

[0039]FIG. 4 represents a substrate with the cuttings of windows

[0040]FIG. 5 represents the superimposition of the substrate on theassembly of the conductive film with the glue film,

[0041]FIG. 6 represents a section of a card or an electronic label witha mounted electronic component.

[0042]FIG. 7 represents a section of a card or an electronic label withan electronic component that has one contact connected to the conductivelayer by means of a bridge.

[0043]FIG. 8 represents a section of a card or an electronic label withan electronic component that has one contact connected to the conductivelayer by means of a bridge coming from the opposite side of thesubstrate.

[0044] FIGS. 1 to 6 illustrate the details of the manufacturing methodof a card or an electronic label, according to the invention, with theresults obtained after each step of the method.

[0045]FIG. 1 shows the cutting of windows (2) in an adhesive film (1)carried out by stamping for example. The shape and dimensions of thewindows depend on the electronic components to be mounted later. Saidadhesive film constitutes the adhesive layer.

[0046] The cut adhesive film (1) is superimposed and assembled on a filmof conductive material (4) to form the assembly (3) comprising theadhesive layer and conductive layer disclosed in FIG. 2. The conductivematerial is generally copper. Therefore, the latter appears in thewindows (2) of the assembly (3).

[0047] The following step is the cutting by stamping or engraving ofsegments (6) in the windows (2) of the assembly (3) comprising theadhesive layer and conductive layer that permits separate contactsurfaces (4′) to be prepared for the electronic components. In this waythe assembly (5) is obtained. The object of this type of a cutting is tocreate a separation between two conductive material areas that are stillelectrically connected by means of the surrounding conductive surface.

[0048]FIG. 4 shows an insulating material substrate (7) whose thicknessis selected according to the maximum height of the electronic componentsto be mounted. In this substrate, windows (8) are cut to correspond tothe form and dimensions of these components. These windows are generallysimilar to those cut in the adhesive film in FIG. 1.

[0049] The substrate (7) cut in this way is superimposed and assembledon the assembly (3) comprising the adhesive layer and conductive layerin order to make the windows (8) of the substrate correspond with thewindows (2) of the assembly comprising the adhesive layer and conductivelayer. The result obtained constitutes a substrate assembly (9),comprising an adhesive layer and conductive layer, that is representedin FIG. 5. An enlarged view of the substrate face illustrates windows(2) and (8) superimposed and through which it is possible to distinguishthe conductive contact surfaces (4′) reserved for the component to bemounted.

[0050] One step, not illustrated, is the engraving of a circuit on theconductive face (on the back of assembly (9) obtained previously) madeup of a plurality of tracks whose arrangement depends on the electroniccomponents and their contacts. The engraving method used, stamping,machining or chemical etching essentially depends on circuitconfiguration and on the materials used for the substrate and/or for theconductive film.

[0051] The component is then housed in the substrate's window (8)provided for that purpose and then connected for example by soldering,cold or hot conductive bonding to the contact surfaces (4′) orthermo-compression.

[0052] The final result is shown in the enlarged section of FIG. 6 whereit is possible to distinguish the conductive layer made up of theconductive film (4) assembled on the substrate (7) with adhesive film(1) that forms the adhesive layer. The component (11) is housed in thewindow (2) of the adhesive film (1) superimposed on the window (8) ofsubstrate (7), the contacts (10) of said component are connected toconductive surfaces (4′) separated by the segment (6).

[0053]FIG. 7 shows an electric bridge (12) that connects an electroniccomponent contact (11) to a track positioned at a distance on theconductive layer (4). Said bridge passes over the other tracks (13) andis electrically insulated from the latter by means of a protectivematerial (14). This protective material is generally made up of a thinfilm piece of insulating material. The other component contact isdirectly connected on the conductive layer as in FIG. 6.

[0054]FIG. 8 shows an electric bridge (15) that is connected to anelectronic component contact (11) passing close to the latter throughthe substrate. This bridge is then connected to a connection area (16)located on the opposite side of the substrate; said area is formed by aconductive element (17) that passes through the substrate. This element(17) is connected to the conductive layer (4).

[0055] A final optional step, not illustrated, for card or electroniclabel manufacturing consists in assembling a film of insulating materialon each face in order to protect the assembly, illustrated in FIG. 6,from humidity or corrosion and moreover, to allow adequate marking(logo, characters, image etc.)

[0056] A variant of the card or the electronic label, not illustrated,according to the invention, is constituted by the assembling on asubstrate of an adhesive layer and a conductive layer on eachsubstrate's face. The substrate includes at least one window wherein anelectronic component is housed. The adhesive layers maintain theconductive layers on each side of the substrate and at least oneconductive layer extends partially into the surface of the window insuch a way as to form at least one electrical contact. The electroniccomponent contacts are connected, either by means of a bridge with atleast one of the conductive layers covering the substrate, or by directconnection on the contact surface located in the window's substrate.

[0057] The substrate thickness of a card produced according to themethod described by the invention can be compared to the maximum heightof one or more electronic components even if these have a relativelyhigh height. This is particularly the case for components such asbatteries or displays. Therefore, this type of card can have severalmillimeters thickness, in particular when a great rigidity is desired.

1-11. (canceled).
 12. Method for manufacturing cards or electroniclabels carried out by assembling at least one thin, flexible substrate(7), a conductive layer (4) and an adhesive layer (1), and comprising atleast one electronic component (11), said conductive layer (4) beingmade up of conductive tracks defining an antenna, characterized in thatit includes the following steps: formation of at least one segment (6)in the conductive layer (4), formation of at least one window (2) in theadhesive layer (1), formation of at least one window (8) in thesubstrate (7), said window (8) being intended to receive the electroniccomponent (11), superimposition and lamination of the adhesive (1) andconductive layers (4) on the substrate (7) in order to make correspondthe openings (6), (2), (8) made previously. realization of an electriccircuit made up of a plurality of tracks, and formation of at least oneconnection surface (4′) for the electronic component (11) located in thewindow of the substrate (7), positioning and connection (10) of theelectronic component (11) in the window (8) formed for that purpose inthe substrate (7).
 13. Method according to claim 12, characterized inthat the adhesive layer (1) is made up of an adhesive film.
 14. Methodaccording to claim 12, characterized in that the adhesive layer (1) isapplied by silk-screening on the conductive layer with protected areasto form the windows.
 15. Method according to claim 12, characterized inthat the adhesive layer is applied by silk-screening onto the substrate,preferably with protected areas to form the windows.
 16. Methodaccording to claim 12, characterized in that the realization of theelectric circuit is carried out by stamping, machining or chemicaletching of the conductive layer (4).
 17. Method according to claim 12,characterized in that the connection (10) of said electronic component(11) is carried out by means such as soldering, cold or hot conductivebonding on the conductive film, or thermo-compression.
 18. Methodaccording to claim 12, characterized in that the formation of thewindows (2), (8) in the adhesive layer (1), the substrate (7) and thesegment (6) in the conductive layer (4) is carried out by stamping. 19.Method according to claim 12, characterized in that the conductive layer(4) is deposited so as to extend partially into the window's surface (8)by forming at least two electronic contacts (4′) on which the electroniccomponent (11) is connected.
 20. Method according to claim 12,characterized in that the conductive layer (4) is deposited in such away as to extend into the surface of the window (8) forming at least oneelectric contact (4′) on which the electronic component (11) isconnected, and another electric contact is formed by means of a bridge(12, 15) connecting a more distant connection area on the conductivelayer (4).
 21. Method according to any of the claims 12 to 20,characterized in that the thickness of the substrate (7) is at leastequal to the height of the highest electronic component (11).
 22. Methodaccording to any one of the claims 12 to 20, characterized in that afinal step consists in assembling a film of insulating material on eachface of the assembly, said film serving as protection and/or supportallowing a marking to be made.
 23. Method according to claim 21,characterized in that a final step consists in assembling a film ofinsulating material on each face of the assembly, said film serving asprotection and/or support allowing a marking to be made.